This invention relates to release coatings made from selected modified starch esters and more particularly starch esters having an ester component of 2 to 8 carbon atoms and an intermediate DS of from 1.0 to 2.2.
Release coatings generally comprise compositions and/or agents that control or eliminate the adhesion between two surfaces. These coatings typically have good release characteristics, which is the capacity of permitting an adhesive material sticking to a surface to peel off easily (i.e., it must provide low interfacial tension with the adhesive mass to which it is in contact). However, good release properties are not the only characteristic desired in such materials. Other characteristics needed in release coatings include good cohesive strength, good adhesion with the backing member substrate and no contamination or component migration into the adhesive layer.
Silicone materials such as organosiloxanes are well known for their use as release agents and coatings. U.S. Pat. No. 4,983,701 issued Jan. 8, 1991, U.S. Pat. No. 5,356,706 issued Oct. 18, 1994 and U.S. Pat. No. 5,376,420 issued Dec. 27, 1994 all disclose the use of silicone materials as release agents in different applications. Other types of release agents which have been used include synthetic polymers such as polyolefins and fluorocarbons, long chain alkyl derivatives such as fatty ester synthetic waxes and fatty acids and waxes such as petroleum, vegetable and animal waxes.
While the materials exemplified above and particularly the silicone materials have been shown to have suitable release characteristics for various applications, they are not useful when repulpable, recyclable paper products are desired.